With increasing popularity of renewable energy exploitation hybrid devices—combing fossil and renewable power generation—like the incipiently mentioned assembly enter the focus of interest in the field of power generation. Renewable energy including solar energy naturally leads to unwanted power generation fluctuation to be compensated. These hybrid devices aim to reduce fossil fuel consumption and power generation fluctuations coming with renewable power generation.
A combination of a gas turbine with a solar receiver as defined incipiently is assumed to be prior art.
Solar receivers for gas turbines as defined above have a limited maximum temperature at around 800° C. to 1000° C. Since the gas turbine inlet temperature for modern gas turbines is around 1200° C. to 1500° C. and since the efficiency of a gas turbine (upper limit is Carnot efficiency ηc=1−Tmin/Tmax) depends on the maximum temperature operating a gas turbine—a reduced maximum inlet temperature of 1000° C. results in a significant efficiency reduction of the gas turbine. It is therefore reasonable to provide a supplementary combustion downstream the solar receiver to achieve an adequate turbine inlet temperature. This supplementary combustion also covers for situations with less solar energy to operate the gas turbine with a reasonable efficiency by said supplementary combustion.
When a conventional combustor is placed downstream said solar receiver it receives gas of much more elevated temperature than it would receive from a normal gas turbine compressor in a conventional layout. These circumstances exclude existing combustion systems which might experience an elevated risk of combustion instability such as auto ignition and flashback. Existing combustion systems also give a comparatively high pressure drop and experience higher metal temperature than designed for if being part of such an assembly. A further issue is that the fuel to air ratio is much lower than in existing combustions systems resulting in a higher likelihood of instability.